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Irecently bought a 2001 TH62 with a known transmission fault. The seller thoughtit was torque convertor but I want to rule out electrics first. Initially itdidn't drive at all but I was able to get a couple of forward gearsto shift it a bit and I obtained a reverse gear twice. So it can get gearsoccasionally but intermittent which is why I think electrical. Ive checked thehandbrake neutraliser and foot brake neutraliser and they seem ok. I have been able to get 1st(2nd or 3rd Ė more likely to be 3rd) and 4thforward but no reverse. I took the fwd/rev lever to bits Ė some wear on thecontacts but Iíve been able to tweak this in the short term to ensure contact ĖI now consistently get the rev alarm when selected as this was intermittent before.Trans oil level is fine. I then went and removedthe solenoids and swapped a known good one onto solenoid A (reverse_ no difference. Top-bottom solenoids Ė A Reverse, D Fwd Low,E Fwd High 4th, C 1st and E 2nd and 3rd. The bottom two solenoids C & B werehard to remove (almost like they were energised) but they were still like thiswhen I disconnected the cables. A whiteresidue was on the shaft. Iíve been able to lightly clean this with diesel andwet paper. Solenoid shaft E was marked but removed ok. All solenoids now fit onand off the shafts fine but I may need to replace some shafts as thecoating/chrome is poor. Once Iíd cleaned up thesolenoids I was able to get 1st rev (I have the machine off thefloor now) but it is a bit pathetic. I canít get rev in 2nd or 3rd.With the machine off thefloor I tried the fwd gear and it appears as If I have 1st. When Iselect 2nd I still get fw rotation but I suspect this is actually 3rdas I donít see any increase when I select 3rd but it is much fasterthan 1st and it steps up again for 4th Ė so I donít thinkIím getting 2nd. With all the solenoidsremoved, Iíve selected each gear and checked which ones generate a magneticfield. 1st fwd selected, I should have B,C & D energised, whichI do. 2nd Fwd Selected, I should have B & D Energised but I onlyget D Energised. 3rd fwd selected, I should have just D energisedwhich I do have Ė Iím only getting D energised with 2nd which is whyI think itís actually 3rd and I donít see any change in speedsbetween the two selections. 4th Fwd should energise D and E which Iget with much higher tyre speed. So in Fwd I have a fault with solenoid B beingpowered yet I know that in other gears this solenoid gets power. In neutral no solenoidsare powered. I selected 1st Rev and I should get solenoid A rev andB and C energized. I do get all three but as I say pretty poor response Ė need torev the engine hard. 2nd Rev should energise solenoid A & B butI only get A but not motion. 3rd Rev should energise A on its ownwhich I get but no motion. There shouldnítbe a 4th rev but I get solenoid A and E and no motion. Anyone know where tostart? I would try swapping the hand lever in the cab but these are expensiveand I need to prove itís this before proceeding. Anyone checked pressures from thetests ports and adjusted them? I want to make sure the electrics and pressuresare fine before I think about torque convertor. Iíve had the inspection plate off the bottom of the bell housing and Ican see the convertor. Canít see any damage or leaking oil. Same trans I think on allthe Cat TH A-Series. Many thanks

Sorry no-one has offered any help yet, do you know the make of transmission fitted is it Caterpillar's own? or ILT or Clark Hurth? If it is the same as another make of machine you might get more info than if it's cat's own as they aren't that popular over here.

Sorry no-one has offered any help yet, do you know the make of transmission fitted is it Caterpillar's own? or ILT or Clark Hurth? If it is the same as another make of machine you might get more info than if it's cat's own as they aren't that popular over here.

Its a good old clark hurth T12000. I do check in here fairly regular but missed this post.

Irecently bought a 2001 TH62 with a known transmission fault. The seller thoughtit was torque convertor but I want to rule out electrics first. Initially itdidn't drive at all but I was able to get a couple of forward gearsto shift it a bit and I obtained a reverse gear twice. So it can get gearsoccasionally but intermittent which is why I think electrical. Ive checked thehandbrake neutraliser and foot brake neutraliser and they seem ok. I have been able to get 1st(2nd or 3rd Ė more likely to be 3rd) and 4thforward but no reverse. I took the fwd/rev lever to bits Ė some wear on thecontacts but Iíve been able to tweak this in the short term to ensure contact ĖI now consistently get the rev alarm when selected as this was intermittent before.Trans oil level is fine. I then went and removedthe solenoids and swapped a known good one onto solenoid A (reverse_ no difference. Top-bottom solenoids Ė A Reverse, D Fwd Low,E Fwd High 4th, C 1st and E 2nd and 3rd. The bottom two solenoids C & B werehard to remove (almost like they were energised) but they were still like thiswhen I disconnected the cables. A whiteresidue was on the shaft. Iíve been able to lightly clean this with diesel andwet paper. Solenoid shaft E was marked but removed ok. All solenoids now fit onand off the shafts fine but I may need to replace some shafts as thecoating/chrome is poor. Once Iíd cleaned up thesolenoids I was able to get 1st rev (I have the machine off thefloor now) but it is a bit pathetic. I canít get rev in 2nd or 3rd.With the machine off thefloor I tried the fwd gear and it appears as If I have 1st. When Iselect 2nd I still get fw rotation but I suspect this is actually 3rdas I donít see any increase when I select 3rd but it is much fasterthan 1st and it steps up again for 4th Ė so I donít thinkIím getting 2nd. With all the solenoidsremoved, Iíve selected each gear and checked which ones generate a magneticfield. 1st fwd selected, I should have B,C & D energised, whichI do. 2nd Fwd Selected, I should have B & D Energised but I onlyget D Energised. 3rd fwd selected, I should have just D energisedwhich I do have Ė Iím only getting D energised with 2nd which is whyI think itís actually 3rd and I donít see any change in speedsbetween the two selections. 4th Fwd should energise D and E which Iget with much higher tyre speed. So in Fwd I have a fault with solenoid B beingpowered yet I know that in other gears this solenoid gets power. In neutral no solenoidsare powered. I selected 1st Rev and I should get solenoid A rev andB and C energized. I do get all three but as I say pretty poor response Ė need torev the engine hard. 2nd Rev should energise solenoid A & B butI only get A but not motion. 3rd Rev should energise A on its ownwhich I get but no motion. There shouldnítbe a 4th rev but I get solenoid A and E and no motion. Anyone know where tostart? I would try swapping the hand lever in the cab but these are expensiveand I need to prove itís this before proceeding. Anyone checked pressures from thetests ports and adjusted them? I want to make sure the electrics and pressuresare fine before I think about torque convertor. Iíve had the inspection plate off the bottom of the bell housing and Ican see the convertor. Canít see any damage or leaking oil. Same trans I think on allthe Cat TH A-Series. Many thanks

Hello

Sorry for the late reply, please see the incredibly small picture attached! hope you can zoom in!

This is the solenoid sequence for the T12000 box as used in a Manitou and matbro handler, i'm 99% sure the sequence is the same for the cat.

Aha, I've overhauled one of them. Most likely the plates have delaminated which gives intermittent gears or no gears depending on where the broken bits of lining are at any one time.. It'll need a full rebuild. PM me an email address and I'll send you the workshop manual if you need it. Ace could probably get you the parts as well as the manual.

Gauges were for a full shakedown before refitting the cab. You could get away with a minimum of three gauges but it's handier to have six. If you have pressure in the test ports but no drive the plates have broken up. You need to know what clutches are used in each gear as some gears use three clutches any one of them away= no drive. Replace all the plates not just the ones that a re away this week or you'll be back in it shortly. Parts were around £1k a few years ago including plates and piston seals and other seals etc. Pay attention to the wee needles roller bearing on the inner end of the input shaft as it's prone to wear.